Many industries utilize high carbon materials, commonly referred to as coke, to make a variety of products, including steel and other metals. To be utilized, coke must meet rigorous physical and chemical specifications for moisture, volatiles, ash, sulfur, phosphorous, alkalies, and carbon content. Production of coke requires the carbonization of coal through pyrolization, a thermal process. It is typically a time consuming and expensive process.
Cheaper coals, commonly referred to as low rank coals (LRCs), which include, for example, brown coal, lignite, and subbituminous coal, have been unsuitable for producing coke. This is primarily due to their low thermal values, which are primarily a reflection of their high moisture content, and lack of agglutinating properties making them unsuitable for the production of coke. This being so, low volatile bituminous coals (LVBs), rather than LRCs, have historically been used as feedstock for coke production. Because no single type of LVB has the requisite chemical and physical specifications to serve as a feedstock, a blend of prepared LVBs must typically be used to produce coke. Given the limited resources and relative costliness of LVBs as compared with LRCs, there is a need for developing a method for using a more cost effective source of coal, such as LRCs, rather than LVBs in the production of coke.
Existing methods of coke production are time consuming and inefficient. Traditionally, producing coke requires four separate batch operations: (1) blending of a variety of raw or prepared LVBs (2) charging a slot oven, (3) heating the charge at a high temperature throughout the ‘coking’ period, (4) pushing hot coke from the oven onto a wharf to cool. These operations normally require more than 15 hours to complete. Efficiency and throughputs are constrained by the quality of the feedstock, especially particle size, bulk density, and coking properties such as swelling, softening, and solidification. Hence, there is a need in the industry for developing a more efficient, less time consuming, and cheaper method of producing coke.
Methods of coke production are also historically associated with high environmental costs. Coke production requires the pyrolization of the carbonized materials through a thermal process. Such thermal processe typically produces significant organic vapors that escape into the atmosphere during the coking cycle. Costly environmental controls are required to capture and treat these to meet environmental regulations. Hence, there is a need in the industry for a method of producing coke that does not expose hot coke or release organic vapors to the atmosphere.